The present invention generally refers to a blowing molding machine, and in particular to a blow molding machine of a type having a base frame without tie bars for the production of blow-molded hollow plastic bodies, in which two blow mold halves for receiving the tubular parison are displaceable in horizontal direction by means of a transport device acting on the mold support plates or on the associated support columns carrying the mold support plates, and which has an independent separate locking system acting on the mold support plates and having its own drive for pinching off the tubular parison and for locking the blow mold halves during the blow molding operation.
German Patent No. 34 16 871 C3 discloses a blow molding machine of this type which is notable for its simple housing design without tie bars, in which the moving masses are considerably reduced compared with other conventional blow molding machines through decentralization of the movement systems and provision of a separately operating transport device and an independent locking system. Both movement systems are hydraulically driven. The blow mold halves are coupled to one another by way of a mechanical synchronizing device which includes a rack-and-pinion combination. An asynchronous actuation of the blow mold halves with respect to one another is not possible.
It is also known from German Pat. No. 16 04 575 to provide a blow molding machine with electrical drive of the blow mold halves or of the two support columns carrying the blow mold halves. The drive and synchronization of the blow mold halves is effected by way of four right-hand/left-hand rotatable threaded spindles having threads of different design (right-hand/left-hand threads) which are guided through threaded bores in the support columns.
The two support columns are coupled directly in positive-locking manner by way of these rotatable threaded spindles acting as a synchronizing device. The threaded spindles are driven by an electric motor by way of a toothed wheel/chain combination. As a result, the blow mold halves always execute synchronous opening and closing movements. This design does also not permit an asynchronous movement of the blow mold halves with respect to one another so that this type of blow molding machine is no longer able to meet current demands, since the translatory movement of the support columns is effected by way of track wheels on ground rails and a precise guidance of the blow mold parts in a manner free from play and free from tilting is not guaranteed. Such a blow molding machine cannot be constructed as a machine with two or more stations.